Negative Pressure Wound Therapy Dressings Research Articles

Incisional negative pressure wound therapy dressings (iNPWTd) in routine primary hip and knee arthroplasties: A randomised controlled trial.

ObjectivesWound complications are reported in up to 10% hip and knee arthroplasties and there is a proven association between wound complications and deep prosthetic infections. In this randomised controlled trial (RCT) we explore the potential benefits of a portable, single use, incisional negative pressure wound therapy dressing (iNPWTd) on wound exudate, length of stay (LOS), wound complications, dressing changes and cost-effectiveness following total hip and knee arthroplasties.MethodsA total of 220 patients undergoing elective primary total hip and knee arthroplasties were recruited into in a non-blinded RCT. For the final analysis there were 102 patients in the study group and 107 in the control group.ResultsAn improvement was seen in the study (iNPWTd) group compared to control in all areas. Peak post-surgical wound exudate was significantly reduced (p = 0.007). Overall LOS reduction (0.9 days, 95% confidence interval (CI) -0.2 to 2.5) was not significant (p = 0.07) but there was a significant reduction in patients with extreme values of LOS in the iNPWTd group (Moses test, p = 0.003). There was a significantly reduced number of dressing changes (mean difference 1.7, 95% CI 0.8 to 2.5, p = 0.002), and a trend to a significant four-fold reduction in reported post-operative surgical wound complications (8.4% control; 2.0% iNPWTd, p = 0.06).ConclusionsBased on the results of this RCT incisional negative pressure wound therapy dressings have a beneficial role in patients undergoing primary hip and knee arthroplasty to achieve predictable length of stay, especially to eliminate excessive hospital stay, and minimise wound complications.Cite this article: S. L. Karlakki, A. K. Hamad, C. Whittall, N. M. Graham, R. D. Banerjee, J. H. Kuiper. Incisional negative pressure wound therapy dressings (iNPWTd) in routine primary hip and knee arthroplasties: A randomised controlled trial. Bone Joint Res 2016;5:328–337. DOI: 10.1302/2046-3758.58.BJR-2016-0022.R1

Influence of Negative-Pressure Wound Therapy on Tissue Oxygenation in Diabetic Feet.

Negative-pressure wound therapy (NPWT) has become a common wound care treatment modality for a variety of wounds. Several previous studies have reported that NPWT increases blood flow in the wound bed. However, NPWT might decrease tissue oxygenation in the wound bed because the foam sponge of NPWT compresses the wound bed under the influence of the applied negative pressure. Adequate tissue oxygenation is an essential consideration during diabetic foot management, and the foot is more sensitive to ischemia than any other region. Furthermore, the issue as to whether NPWT reduces or increases tissue oxygenation in diabetic feet has never been correctly addressed. The aim of this study was to evaluate the influence of NPWT on tissue oxygenation in diabetic feet. Transcutaneous partial oxygen pressures (TcPO2) were measured to determine tissue oxygenation levels beneath NPWT dressings on 21 feet of 21 diabetic foot ulcer patients. A TcPO2 sensor was fixed at the tarsometatarsal area of contralateral unwounded feet. A suction pressure of -125 mm Hg was applied until TcPO2 reached a steady state. The TcPO2 values for diabetic feet were measured before, during, and after NPWT. The TcPO2 levels decreased significantly after applying NPWT in all patients. Mean TcPO2 values before, during, and after therapy were 44.6 (SD, 15.2), 6.0 (SD, 7.1), and 40.3 (SD, 16.4) mm Hg (P < .01), respectively. These results show that NPWT significantly reduces tissue oxygenation levels in diabetic feet.

Antibiotic Irrigation and Prophylactic Negative Pressure Wound Therapy to Reduce Surgical Site Infections [20E

INTRODUCTION: We evaluated a quality improvement protocol (QI) to reduce surgical site infections (SSI) in patients undergoing laparotomy. METHODS: The QI included antibiotic irrigation (AI) following fascial closure and prophylactic negative pressure wound therapy dressing (NPWT) applied to the skin. A retrospective analysis was performed on cases between 1/2011–7/2014. We evaluated SSI in the sixty-day postoperative period prior to and after the introduction of QI. Patient, operative characteristics, and rate of SSI were compared. Adjusted odds for SSI were examined with logistic regression. RESULTS: 48 QI patients were compared to 72 patients receiving standard care. In the QI group as compared to the standard care group there was higher estimated blood loss (median 500 mL versus 300 mL, P=.05) and higher rate of intraoperative transfusion (47.9% of cases versus 23.6% of cases with transfusion, P<.01). SSI were seen in 6.3% of the QI group versus 14.1% of the standard care group, P=.24. On multivariate logistic regression, the odds of SSI were 86% lower in patients receiving the QI, (OR 0.12, P=.03), after controlling for age, transfusion, preoperative infection and length of surgery. Increased odds of SSI were seen with increasing age, (OR 1.07, P=.04), and intraoperative transfusion, (OR 5.90, P=.03). Post-hoc power calculation revealed 25% power to evaluate this intervention to reduce surgical site infection based on the observed effect size. To detect a 50% reduction in SSI, with 80% power at alpha 0.05, would require n=300 patients in each group. CONCLUSION: Further investigation of AI combined with NPWT to reduce SSI is warranted.

Closed Incision Negative Pressure Wound Therapy vs Conventional Dry Dressings After Primary Knee Arthroplasty: A Randomized Controlled Study

BackgroundThe purpose of this study was to assess the effect of negative pressure wound therapy (NPWT) on quality of life (QoL), wound complications, and cost after primary knee arthroplasty. MethodsA prospective analysis of 33 patients undergoing primary knee arthroplasty performed by 3 surgeons in one institution. The first 12 patients (3 bilateral and 9 unilateral) had conventional dry dressings (CDD) applied and cost of dressings was assessed. The other 21 patients all underwent bilateral knee arthroplasty and had either side randomized to receiving NPWT or CDD. Cost of dressings, wound complications, and QoL were compared. ResultsOne patient had a reaction to the NPWT requiring readmission. Another had persistent wound drainage that required NPWT application. There were no wound issues in the remaining 31 patients. The average cost in the first 12 patients was Australian dollar $48.70 with an average of 1.5 changes on ward. In the 21 patients receiving both dressings, the average cost for CDD was less (Australian dollar $43.51 vs $396.02, P ≤ .011, effect size [ES] = 1.06). When comparing QoL factors, wound leakage (0.14 vs 0.39 P = .019, ES = 1.02), and wound protection (0.16 vs 0.33, P = .001, ES = 0.021) were better in the NPWT group. There was no other significant difference in QoL factors. The average number of changes on the ward was less for the NPWT group (1.19 vs 1.38, P = .317, ES = 1.02). ConclusionWe found no benefit in wound healing or cost with NPWT post knee arthroplasty. There was some benefit in NPWT QoL factors less wound leakage and better protection.

Extra-large negative pressure wound therapy dressings for burns – Initial experience with technique, fluid management, and outcomes

ObjectiveThe use of negative-pressure-wound-therapy (NPWT) is associated with improved outcomes in smaller burns. We report our experience using extra-large (XL) NPWT dressings to treat ≥15% total body surface area (TBSA) burned and describe our technique and early outcomes. We also provide NPWT exudate volume for predictive fluid resuscitation in these critically ill patients. MethodsWe retrospectively reviewed patients treated with XL-NPWT from 2012 to 2014. Following excision/grafting, graft and donor sites were sealed with a layered NPWT dressing. We documented wound size, dressing size, NPWT outputs, graft take, wound infections, and length of stay (LOS). Mean NPWT exudate volume per %TBSA per day was calculated. ResultsTwelve burn patients (mean TBSA burned 30%, range 15–60%) were treated with XL-NPWT (dressing TBSA burned and skin graft donor sites range 17–44%). Average graft take was 97%. No wound infections occurred. Two patients had burns ≥50% TBSA and their LOS was reduced compared to ABA averages. XL-NPWT outputs peaked at day 1 after grafting followed by a steady decline until dressings were removed. Average XL-NPWT dressing output during the first 5 days was 101±66mL/%BSA covered per day. 2 patients developed acute kidney injury. ConclusionThe use of XL-NPWT to treat extensive burns is feasible with attention to application technique. NPWT dressings appear to improve graft take, and to decrease risk of infection, LOS, and pain and anxiety associated with wound care. Measured fluid losses can improve patient care in future applications of NPWT to large burn wounds.

Negative pressure wound therapy dressings

There are many different forms of negative pressure wound therapy dressings and it is important to distinguish clearly between each type. They enable the treatment to be adapted to the shape and depth of the wound, its degree of exudation and the persistence of the fibrinous areas on the surface. The machine's traction capacity, measured in mm of mercury (Hg), must be controlled to establish the healing profile: the more powerful the machine and the more contact there is between the foam and the wound, the faster the formation of the granulation tissue. There are many different solutions which are implemented in accordance with the clinical assessment of the wound.

ADding negative pRESSure to improve healING (the DRESSING trial): a RCT protocol

IntroductionObese women are more likely to develop a surgical site infection (SSI) following caesarean section (CS) than non-obese women. Negative pressure wound therapy (NPWT) is increasingly being used to reduce...

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Negative pressure wound therapy for high-risk wounds in lower extremity revascularization: study protocol for a randomized controlled trial.

BackgroundRates of surgical site infections (SSIs) following groin incision for femoral artery exposure are much higher than expected of a clean operation. The morbidity and mortality is high, particularly with the use of prosthetic grafts. The vascular surgery population is at an increased risk of SSIs related to peripheral vascular disease (PVD), diabetes, obesity, previous surgery and presence of tissue loss. Negative pressure wound therapy (NPWT) dressings have been used on primarily closed incisions to reduce surgical site infections in other surgical disciplines. We have not come across any randomized controlled trials to support the prophylactic use of negative pressure wound therapy in high-risk vascular patients undergoing lower limb revascularization.Methods/designIn this single-center, prospective randomized controlled trial, patients scheduled for a lower limb revascularization requiring open femoral artery exposure who are at a high risk (BMI > 30 kg/m2, previous femoral cutdown or Rutherford V or VI category for chronic limb ischemia) will be eligible for the study. A total of 108 groin incisions will be randomized to the use of a negative pressure wound device or standard adhesive gauze dressing. Patients will be followed in hospital and reassessed within the first 30 days postoperatively. The primary outcome is SSI within the first 30 days of surgery and will be determined using the intention-to-treat principle. Secondary outcomes include length of stay, emergency room visits, reoperation, amputation and mortality. A cost analysis will be performed.DiscussionThe trial is expected to define the role of NPWT in SSI prophylaxis for lower limb revascularization in high-risk vascular patients. The results of the study will be used to inform current best practice for perioperative care and the minimization of SSIs.Trial registrationNCT02084017, March 2014

Changes in the management of deep sternal wound infections: a 12-year review.

Deep sternal wound infection (DSWI) is a rare but life-threatening complication following cardiac surgery associated with increased morbidity and mortality. Management of these patients has evolved over the years and can include sternal rewiring, mediastinal irrigation, negative-pressure wound therapy (NPWT) dressing or repair with flaps. We reviewed changes in our management of DSWI and outcomes. Using the Australian and New Zealand Society of Cardiac and Thoracic Surgeons database, 5472 underwent cardiac surgery at St Vincent's Hospital, Melbourne, and 42 were identified as developing DSWI requiring re-operation between June 2002 and September 2014. Data were collected pertaining to risk factors for DSWI, management strategies and outcomes. Patients were compared from a period prior to NPWT dressing use (June 2002-February 2006, n = 14) and since the NPWT has been used regularly in the management of DSWI (from March 2006, n = 28). Patients were also compared based on the requirement for flap closure of their sternal wound. Because of the widespread use of NPWT dressings, there is a trend towards fewer sternal infections requiring flap closure (25 versus 42.8%) and less post-operative complications after definitive closure (7.1 versus 28.6%). Before and after widespread NPWT use, patients require similar number of re-operations before closure and have no significant differences in time to definitive closure or length of hospital stay. The use of NPWT dressings as a bridge to definitive closure may reduce the need for more burdensome flap reconstruction, does not delay definitive reconstruction or prolong hospital stay and may reduce post-reconstruction complications requiring re-operation.

Negative pressure wound therapy use to decrease surgical nosocomial events in colorectal resections (NEPTUNE): study protocol for a randomized controlled trial.

BackgroundSurgical site infections (SSIs) are the second most common form of nosocomial infection. Colorectal resections have high rates of SSIs secondary to the inherently contaminated intraluminal environment. Negative pressure wound therapy dressings have been used on primarily closed incisions to reduce surgical site infections in other surgical disciplines. No randomized control trials exist to support the use of negative pressure wound therapy following elective open colorectal resection to reduce surgical site infection.Methods/DesignIn this single-center, superiority designed prospective randomized open blinded endpoint controlled trial, patients scheduled for a colorectal resection via a laparotomy will be considered eligible. Patients undergoing laparoscopic resection will be enrolled but only randomized and included if the operation is converted to an open procedure. Exclusion criteria are patients receiving an abdominoperineal resection or a palliative procedure, as well as pregnant patients and those with an adhesive allergy. After informed consent, 300 patients will be randomized to the use of a standard adhesive gauze dressing or to a negative pressure wound device. Patients will be followed in hospital and reassessed on post-operative day 30. The primary outcome measure is SSI within the first 30 post-operative days. Secondary outcomes include the length of hospital stay, the number of return visits related to a potential or actual SSI, cost, and the need for homecare. The primary endpoint analysis follows the intention-to-treat principle.DiscussionNEPTUNE is the first randomized controlled trial to investigate the role of incisional negative pressure wound therapy in decreasing the rates of surgical site infections in the abdominal incisions of patients following an elective, open colorectal resection. This low-risk intervention may help decrease the morbidity and costs associated with the development of an SSI in our patients.Trial registrationNCT02007018 – clinicaltrials.gov; 5 December 2013Electronic supplementary materialThe online version of this article (doi:10.1186/s13063-015-0817-8) contains supplementary material, which is available to authorized users.

Negative Pressure Wound Therapy on Closed Surgical Wounds With Dead Space: Animal Study Using a Swine Model.

BackgroundClosed incisional wound surgery frequently leaves dead space under the repaired skin, which results in delayed healing. The purpose of this study was to evaluate the effect of negative pressure wound therapy (NPWT) on incisional wounds with dead space after primary closure by evaluating the fluid volume through the suction drain, blood flow of the skin, tensile strength, and histology of the wounds.MethodsBilateral 25-cm-long incisional wounds with dead space were created on the back of 6 pigs by partially removing the back muscle and then suturing the skin with nylon sutures. NPWT (experimental group) or gauze dressing (control group) was applied over the closed incision for 7 days. Analysis of the wound included monitoring the amount of closed suction drain, blood perfusion unit, tensile strength of the repaired skin, and histology of the incision site.ResultsThe drainage amount was significantly reduced in the experimental group (49.8 mL) compared to the control group (86.2 mL) (P = 0.046). Skin perfusion was increased in the experimental group with statistical significance compared to the control group (P = 0.0175). Collagen staining was increased in the experimental group. The tensile strength of the incision site was significantly higher in the experimental group (24.6 N at 7 days, 61.67 N at 21 days) compared to the control group (18.26 N at 7 days, 50.05 N at 21 days) (P = 0.02).ConclusionThis study explains some of the mechanism for using NPWT in closed incision wounds with dead space. It demonstrates that NPWT significantly reduces drainage amount, increases skin perfusion, increases tensile strength, and has the tendency to promote collagen synthesis for closed wound with dead space indicating enhanced healing.

Growth factors, silver dressings and negative pressure wound therapy in the management of hard-to-heal postoperative wounds in obstetrics and gynecology: a review.

PurposeThe last two decades witnessed the development of numerous innovative regimens for the management of patients with abnormally healing and infected wounds. Growth factors, negative pressure wound therapy (NPWT) and antiseptic dressings containing silver are examples of methods with best documented efficacy, being widely used in the treatment of acute and chronic post-traumatic wounds, burns and ulcers of various etiology. As far as obstetrics and gynecology are concerned, prevention and treatment of infected, hard-to-heal postoperative wounds is of crucial importance. This article reviews the available literature to discuss the possibilities for use, efficacy and cost-effectiveness of growth factors, NPWT and silver dressings in the treatment of difficult-to-heal postsurgical wounds in obstetrics and gynecology.Materials and methodsAn extensive search of the English and Polish literature via PubMed and EMBASE databases was undertaken for articles published between January 1960 and April 30, 2014 to identify articles that described and assessed use, efficacy and cost-effectiveness of growth factors, silver dressings and NPWT in patients with hard-to-heal postoperative wounds following obstetric or gynecological surgery.ConclusionsLiterature review regarding the use of growth factors, NPWT and silver dressings suggests that these methods may play an important role in the management of wounds after invasive obstetric and gynecological procedures. Obese patients, patients after vulvectomy or prior radiation therapy may benefit most, however, due to non-numerous randomized reports, prospective studies on the use of above-mentioned methods in the treatment of postsurgical wounds following obstetric and gynecological interventions are required.

Evidence update on prevention of surgical site infection.

Surgical site infection (SSI) is a common healthcare-associated infection and complicates up to 10-20% of operations with considerable strain on healthcare resources. Apart from the widely adopted use of appropriate hair removal, antibiotic prophylaxis, avoidance of hypothermia and perioperative glycaemic control to reduce SSIs, this review has considered new research and systematic reviews, and whether their findings should be included in guidelines. The efficacy of preoperative bathing/showering, antibiotic prophylaxis for clean surgery and perioperative oxygen supplementation to reduce the risk of SSI is still in doubt. By contrast, the use of 2% chlorhexidine in alcohol skin preparation, postoperative negative pressure wound therapy and antiseptic surgical dressings do show promise. Antimicrobial sutures in independent meta-analyses were found to reduce the risk of SSI after all classes of surgery (except dirty) whereas the use of wound guards, or diathermy skin incision (compared with scalpel incision), did not. The incidence of SSI after surgery is not falling. Based on this review of published trials and evidence-based systematic reviews some advances might be included into these care bundles. More research is needed together with improved compliance with care bundles.

Influence of antimicrobial coatings of vacuum-assisted closure dressings on methicillin-resistant Staphylococcus aureus growth kinetics: an in vitro study.

Silver-containing negative-pressure wound therapy (NPWT) foam dressings should reduce the microbial load of infected surgical sites and thereby promote healing. The effects of silver and an experimental copper coating of NPWT dressings on the growth kinetics of methicillin-resistant Staphylococcus aureus (MRSA) were investigated with a focus on the importance of the initial bacterial load and the incubation time. Commercially available foam samples with and without silver coating were inoculated in vitro with six MRSA suspensions differing in bacterial concentration (1.85×10(3) to 1.85×10(8) colony-forming units per milliliter [CFU/mL]). In a second series, uncoated, silver-containing and experimental copper-coated foam samples were inoculated with one MRSA suspension (1.85×10(6) CFU/mL). The MRSA viable counts in the entrapped fluid were evaluated statistically after 1, 3, 7, and 14 d incubation. Silver foam samples reduced MRSA counts by two decimal powers compared with the corresponding inocula. With respect to the uncoated samples, silver coating reduced MRSA concentrations by up to 7 logs, which was significant (p≤0.045) for all groups except the one with the highest MRSA concentration. The antibacterial effect of copper became apparent only after 7 d, but thereafter was far more pronounced than the effects of silver (p<0.01 after 14 d). Antimicrobial-coated foam dressings showed significant in vitro antibacterial properties and thus could be advantageous in the treatment of MRSA-infected incisions.

Negative pressure wound therapy in grade IIIB tibial fractures: fewer infections and fewer flap procedures?

Grade IIIB open tibia fractures are devastating injuries. Some clinicians advocate wound closure or stable muscle flap coverage within 72 hours to limit complications such as infection. Negative pressure wound therapy was approved by the FDA in 1997 and has become an adjunct for many surgeons in treating these fractures. Opinions vary regarding the extent to which negative pressure wound therapy contributes to limb salvage. Evidence-based practice guidelines are limited for use of negative pressure wound therapy in Grade IIIB tibia fractures. This systematic literature review of negative pressure wound therapy in Grade IIIB tibia fractures may substantiate current use and guide future studies. We sought to answer the following: (1) Does the use of negative pressure would therapy compared with gauze dressings lead to fewer infections? (2) Does it allow flap procedures to be performed safely beyond 72 hours without increased infection rates? (3) Is it associated with fewer local or free flap procedures? We conducted a systematic review of six large databases (through September 1, 2013) for studies reporting use of negative pressure wound therapy in Grade IIIB open tibia fractures, including information regarding infection rates and soft tissue reconstruction. The systematic review identified one randomized controlled trial and 12 retrospective studies: four studies compared infection rates between negative pressure wound therapy and gauze dressings, 10 addressed infection rates with extended use, and six reported on flap coverage rates in relation to negative pressure wound therapy use beyond 72 hours. None of the 13 studies was eliminated owing to lack of study quality. Negative pressure wound therapy showed a decrease in infection rates over rates for gauze dressings in two of four studies (5.4% [two of 35] versus 28% [seven of 25], and 8.4% [14 of 166] versus 20.6% [13 of 63]), an equivalent infection rate in one study (15% [eight of 53] versus 14% [five of 16]), and an increased infection rate in the fourth study (29.5% [23 of 78] versus 8% [two of 25]). In terms of the second question regarding infection rates with negative pressure wound therapy beyond 72 hours, eight of 10 studies concluded there was no increase in infection rates, whereas two of 10 reported an increase in infection rates associated with negative pressure wound therapy use beyond 72 hours. Infection rates varied from 0% to 57% in these 10 studies. Five studies reported low infection rates of 0% to 7% and five reported rates of 27% to 57%. The third question (addressed by six studies) regarded the potential decreased use of a soft tissue flap in patients treated with extended negative pressure wound therapy. Flap rates were reduced by 13% to 60% respectively compared with those of historical controls. Grade IIIB tibia fractures by definition required soft tissue procedures. The patients in these six studies had Grade IIIB tibia fractures after the first débridement. However, after extended negative pressure wound therapy, fewer patients required flaps than grading at the first débridement would have predicted. There is an increasing body of data supporting negative pressure wound therapy as an adjunctive modality at all stages of treatment for Grade IIIB tibia fractures. There is an association between decreased infection rates with negative pressure wound therapy compared with gauze dressings. There is evidence to support negative pressure wound therapy beyond 72 hours without increased infection rates and to support a reduction in flap rates with negative pressure wound therapy. However, negative pressure wound therapy use for Grade IIIB tibia fractures requires extensive additional study. Level III, therapeutic study.

Incisional Negative Pressure Wound Therapy in the Prevention of Surgical Site Infection after Vascular Surgery with Inguinal Incisions: Rationale and Design of a Randomized Controlled Trial (INVIPS-Trial)

Background/Aims: Inguinal incisions are a common route of access in vascular surgery. Due to anatomical challenges and a diverse bacterial flora in this area, surgical site infections (SSI) represent a common, debilitating and sometimes life-threatening complication. The INVIPS-Trial evaluates the role of Negative Pressure Wound Therapy (NPWT) on closed inguinal incisions in elective vascular surgery to prevent SSI and other wound complications. Methods: This randomized controlled trial (RCT) registered at ClinicalTrials.gov (Identifier: NCT01913132) compares the effects of a NPWT dressing (PICO, Smith & Nephew, UK) and the center’s standard wound dressing (Vitri Pad, ViTri Medical, Sweden) on postoperative wound complications, especially SSI. The study includes two distinct vascular procedures with different SSI risk profiles: endovascular aortic repair (EVAR) and open surgical approaches involving the common femoral artery (OPEN). Results: Four hundred ninety-five groin incisions in both treatment arms are anticipated to be included in the EVAR group and 147 inguinal incisions in both treatment arms in the OPEN group. Since a large percentage of inguinal vascular procedures in both groups but especially in the EVAR group are performed bilaterally, many patients can serve as their own control by randomly receiving NPWT on one and the standard dressing on the contralateral inguinal incision. Conclusions: This ongoing RCT attempts to elucidate the potential benefit of NPWT on closed inguinal incisions after different vascular procedures. Outcome and conclusions of this trial could have implications on postoperative wound care of patients in both vascular surgery and other surgical specialties.

Influence of negative-pressure wound therapy on tissue oxygenation of the foot.

BackgroundNegative-pressure wound therapy (NPWT) is believed to accelerate wound healing by altering wound microvascular blood flow. Although many studies using laser Doppler have found that NPWT increases perfusion, recent work using other modalities has demonstrated that perfusion is reduced. The purpose of this study was to investigate the influence of NPWT on tissue oxygenation of the foot, which is the most sensitive region of the body to ischemia.MethodsTranscutaneous partial pressure of oxygen (TcpO2) was used to determine perfusion beneath NPWT dressings of 10 healthy feet. The sensor was placed on the tarso-metatarsal area of the foot and the NPWT dressing was placed above the sensor. TcpO2 was measured until it reached a steady plateau state. The readings obtained at the suction-on period were compared with the initial baseline (pre-suction) readings.ResultsTcpO2 decreased significantly immediately after applying NPWT, but gradually increased over time until reaching a steady plateau state. The decrease in TcpO2 from baseline to the steady state was 2.9 to 13.9 mm Hg (mean, 9.3±3.6 mm Hg; 13.5±5.8%; P<0.01). All feet reached a plateau within 20 to 65 minutes after suction was applied.ConclusionsNPWT significantly decrease tissue oxygenation of the foot by 2.9 to 13.9 mm Hg. NPWT should be used with caution on feet that do not have adequate tissue oxygenation for wound healing.

Negative-pressure wound therapy after fasciotomy reduces muscle-fiber regeneration in a pig model.

Negative-pressure wound therapy (NPWT) can improve fasciotomy wound closure, but its effects on skeletal muscle are largely unknown. The purpose of this study was to evaluate NPWT effects on skeletal muscle after fasciotomy for compartment syndrome in an animal model and to assess regional variability in muscle fiber regeneration. Compartment syndrome was induced in the hindlimb of twenty-two adult female pigs with use of a continuous intracompartmental serum-infusion model. Fasciotomy was performed after six hours, and animals were randomized to receive either wet-to-dry gauze dressings (control group) or NPWT dressings (-125 mm Hg, continuous suction) for seven days. Delayed primary wound closure was attempted at seven days, and the peroneus tertius was harvested for analysis seven days or twenty-one days after fasciotomy. Muscles were weighed, and hematoxylin and eosin-stained samples from four regions of the muscle (superficial central, deep central, lateral, and proximal) were mapped for different cellular morphologies. Muscle weight was greater in the affected limb at all time points with no difference between treatment groups. At seven days, only the deep central samples in the NPWT group had a significantly greater cross-sectional area containing normal fibers as compared with that found in the controls. By twenty-one days, the deep central, lateral, and proximal regions of the NPWT-treated muscles had a smaller cross-sectional area containing normal fiber morphology and a greater cross-sectional area containing only mononucleated cells as compared with the controls. NPWT did not decrease muscle weight. At twenty-one days, the extent of muscle fiber regeneration after fasciotomy for compartment syndrome was reduced in muscles treated with NPWT for seven days compared with the values in the control group treated with wet-to-dry gauze dressings. NPWT may be harmful to skeletal muscle after compartment syndrome requiring fasciotomy and local wound care.

The flaws of laser Doppler in negative-pressure wound therapy research.

Recent studies, using modalities other than laser Doppler, have indicated that perfusion during negative-pressure wound therapy (NPWT) is reduced, contrary to world literature. The aim of the present study was to evaluate whether the measuring technique of the laser Doppler could be influenced by the compressive nature of NPWT dressings and whether this could explain the conflicting findings. A hypothesis that it may be possible for laser Doppler to record similar readings to those obtained during NPWT by merely compressing tissues manually was tested on 12 NPWT dressings, with each undergoing an alternating series of manual compressive forces and NPWT (-125 mmHg). During the periods of NPWT (n = 12), the mean perfusion recording increased in five experiments, reduced in six, and remained unchanged in one. During the period when manual pressure was applied (n = 12), there was a mean increase in perfusion in six experiments and a reduction in six. The type of change in perfusion (increase or decrease) was the same for both NPWT and manual pressure in 10 of the 12 experiments. In conclusion, laser Doppler can incorrectly record increased perfusion when tissues are compressed, implying that it is flawed in the field of NPWT research as tissues are always compressed to some degree by the NPWT dressing.